Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
Firearms are believed to have been invented around the thirteenth or fourteenth century. At that time, firearms consisted of bamboo rods used to guide shrapnel or other projectiles using the force of combusting gunpowder. Over the years, firearms have evolved tremendously, as have the projectiles fired from firearms.
Many early firearms relied on various forms of shrapnel for projectiles. With the evolution of firearms, bullets, and other projectiles similarly have evolved. With the evolution of the musket and similar firearms, spherical lead balls were used for projectiles as the soft lead could be pushed into the barrel easily and still provided a relatively effective projectile. With the advent of modern firearms, particularly in the early part of the nineteenth century, bullets evolved into pointed or conical projectiles. For example, Norton's bullet, named for John Norton of the British Army, was among the earliest pointed projectiles, the precursor of modern bullets and other projectiles.
In the late nineteenth century, copper jacketing processes were introduced to firearm projectiles. Copper jacketing was used to protect the projectile from melting and/or otherwise deforming in the barrel of the firearm due to pressures and heat in the barrel. Thus, copper jacketing allowed bullets to evolve from flying chunks of lead with limited accuracy, speed, and effectiveness into carefully aimed high speed projectiles that maintained their shape in the barrel and during flight.
In the twentieth century, ballistics technologies took many leaps. In the twentieth century, for example, the spitzer bullet shape was introduced, which essentially corresponds to the shape of the modern rifle bullet. Similarly, boat tail bullets were introduced, which further enhanced the accuracy of bullets, as well other shapes and modifications introduced during this time period. During the twentieth century, evolution of overall bullet shape essentially was completed. Thus, bullet makers began increasing the lethality and/or damaging effect of bullets, particularly in the last half of the twentieth century. In particular, the hollow point was introduced to bullets to increase and/or control the expansion (sometimes referred to as the “mushrooming” effect) of the bullet when penetrating or otherwise encountering a target. The hollow point evolved considerably during the last fifty years or so to provide many types of self-defense and hunting ammunition.
One tradeoff often encountered by bullet makers and designers is that penetration of bullets often must be sacrificed for expansion of the bullet in the target. In some targets, the lack of penetration can limit the effectiveness of the bullet. For example, the bullet may expand to a large size, but not contact any vital organs of a target if the bullet does not penetrate into a body cavity of the target. Thus, while the bullet may damage the cutaneous, subcutaneous, and/or even some internal organs of the target, the bullet may lack the effectiveness to neutralize the target due to a lack of penetration.
Similarly, if penetration is prioritized over expansion, the effectiveness of the bullet can be diminished. In particular, a bullet may penetrate a target or even pass through the target without contacting any vital organs and/or without causing sufficient damage to the vital organs to incapacitate the target. Of course, penetration through the target can create or increase a risk of collateral damage to people or objects in the vicinity of the target. For example, a small caliber bullet may pass through a target and pierce organs without neutralizing the target. In the realm of self-defense ammunition, the goal generally is to provide maximum expansion and maximum penetration to attempt to ensure that a threat is neutralized as quickly as possible. Another goal of self-defense ammunition is to expend as much of the projectiles energy as possible within the target.
Some bullet designs intend to increase the penetration and expansion of bullets by relying on fragmentation of the bullets. One approach to providing a fragmenting projectile is to compress discrete pieces of material together with enough force to create a substantially solid projectile that unpredictably disintegrates when encountering a target. Of course, the reliability of such ammunition is not consistent and the fragmentation of the projectile cannot be carefully controlled (the number of pieces can be controlled, but their path and/or shape may or may not be subject to careful control). Some other approaches to providing fragmenting projectiles may require various geometries that can affect the feeding capabilities of the ammunition with respect to certain firearms.